Nitric oxide (NO) is a crucial mediator of many biological systems, and is known to mediate the control of systemic and pulmonary artery blood pressure, help the immune system kill invading parasites that enter cells, inhibit the division of cancer cells, transmit signals between brain cells, and contribute to the death of brain cells that can debilitate people with strokes or heart attacks. Nitric oxide also mediates the relaxation of smooth muscle present, for example, in the walls of blood vessels, bronchi, the gastrointestinal tract, and urogenital tract. Administration of nitric oxide gas to the lung by inhalation has been shown to produce localized smooth muscle relaxation to treat pulmonary hypertension, pneumonia, hypoxemic respiratory failure of the newborn, etc. without producing systemic side effects.
Inhaled nitric oxide is a potent local pulmonary vasodilator that improves the matching of ventilation with perfusion, thereby increasing the injured lungs oxygen transport efficiency, and raises the arterial oxygen tension. Breathing nitric oxide combines a rapid onset of action occurring within seconds with the absence of systemic vasodilation. Once inhaled, NO diffuses through the pulmonary vasculature into the bloodstream, where it is rapidly inactivated by combination with hemoglobin. Therefore, the vasodilatory effects of inhaled nitric oxide are limited to the pulmonary vasculature. The ability of nitric oxide to dilate pulmonary vessels selectively provides therapeutic advantages in the treatment of acute and chronic pulmonary hypertension. Inhaled NO has also been used to prevent ischemia reperfusion injury after PCI in adults with heart attacks. Inhaled NO can produce systemic anti-inflammatory and anti-platelet effects by increasing the levels of circulating NO biometabolites and other mechanisms.
U.S. Pat. No. 5,396,882 to Zapol, which is incorporated by reference herein, describes electric generation of nitric oxide (NO) from air at ambient pressure for medical purposes. As described in U.S. Pat. No. 5,396,882, an air input port of the system is used for continuously introducing air into the region of the electric arc.